Abstract Forest ecosystems provide essential services such as timber, water regulation, biodiversity, and recreation, yet they are increasingly influenced by the interplay between climate and socioeconomic forces. This study synthesizes findings from the 2020 Resources Planning Act (RPA) Assessment to evaluate how these factors affect historical trends and future projections of U.S. forest conditions and services. Results show that total forest area is projected to decline slightly by 2070, mainly due to conversion to developed land, with the greatest losses occurring in the South. While socioeconomic factors such as population growth, income, and land‐use markets dominate near‐term changes in forest area, timber demand, and recreation, climate change has a larger impact on disturbance patterns, water availability, and forest productivity, particularly under higher warming scenarios. Although overall net changes in forest area are small, land cover data reveal significant losses in interior forests, emphasizing the importance of spatial patterns for biodiversity and ecosystem health. These results illustrate that future forest outcomes depend on the interaction of economic and environmental processes, informing region‐specific management and policy strategies.

Abstract Wildfire extent is growing in the United States (US), a fact attributable to increasingly favorable weather and climatic conditions and the net result of human interventions. US federal land management agencies act upon the wildfire threat by managing hazardous fuels, discouraging human‐caused ignitions, and suppressing active fires. Costs of these actions are rising, so policy makers and wildland managers seek information that can help them understand the trade‐offs of resource allocations. This study generates new information about potential future wildfire and suppression demands by uncovering statistical relationships between observed wildfire and its hypothesized drivers, including socioeconomic, fuels, and climate variables, and by capturing the endogenous relationship between suppression spending and wildfire activity on lands managed by the USDA Forest Service (USFS) and the four key bureaus of the US Department of the Interior (DOI). Climate uncertainty is addressed by modeling wildfire and suppression spending under ten scenarios of potential future climates. Projected wildfire and spending trends to 2100 vary widely across scenarios but are universally upward. When summarized across all ten climate scenarios, real dollar suppression spending rises by a median rate of about 0.87% per year for the USFS and 0.65% per year for the DOI. The highest rates of wildfire and spending growth are projected for the northwestern US.

Sea level rise (SLR) is among the climate-change-related problems of greatest concern, threatening the lives and property of coastal residents and generating far-reaching economic and ecological impacts. We project that SLR will lead to an increase in the rate of new housing construction to replace destroyed structures, impact global wood products supply and demand conditions, and cause changes in global forest sector carbon mitigation potential. Findings indicate that 71 million new units will be built by 2050 to accommodate the SLR-affected global population. More than two-thirds of these new units are projected to be in Asia. The estimated extra wood products needed to build these new residential units is 1,659 million m3, assuming that all these structures would be built mainly with wood, representing a 4 % increase in total wood consumption, compared to projected reference level global wood products consumption. Increased timber removals to meet this higher construction wood demand (alternative scenario) is shown to deplete global forest carbon by 2 % by 2050 compared to the reference scenario. However, all such projected declines in forest biomass carbon could be more than offset by increased carbon sequestration in harvested wood products, avoided emissions due to substitution of wood for non-wood materials in construction, and biomass regrowth on forestland by 2050, with an estimated net emissions reduction benefit of 0.47 tCO2e/tCO2e of extra wood used in SLR-related new houses over 30 years. The global net emissions reduction benefit increased to 2.13 tCO2e/tCO2e of extra wood when price-induced changes in forest land area were included.

The Forest and Rangeland Renewable Resources Planning Act of 1974 (RPA) mandates a periodic assessment of the conditions and trends of the Nation's renewable resources on forests and rangelands.The 2020 RPA Assessment will evaluate the future of the Nation's renewable natural resources through 2070.This publication describes the process used to select a set of four integrated scenarios to represent a plausible span of socioeconomic and climate futures that underpin the natural resource analyses.These four scenarios, and their associated assumptions about population change, economic growth, and climate change, are also described in this document.

The 2020 RPA Assessment includes climate change as a driver affecting natural resources on forests and rangelands in the United States. This publication describes the process used to select the scenarios, climate models, and climate projections that will be used to project renewable resource conditions 50 years into the future. Downscaled climate data selected are the MACAv2-METDATA developed by Abatzoglou and others at the University of Idaho. The dataset covers the conterminous United States at a grid size of approximately 4 km (1/24 degree) on a side. The two selected scenarios are the Representative Concentration Pathways (RCPs) 4.5 and 8.5. Three criteria were used to select the climate models: (1) identification and elimination of poor performing models based on historical climate projections, (2) restriction of selection to only one model from a modeling institution, and (3) selection of a climate model that could provide projections for both the RCP 4.5 and RCP 8.5 scenarios. Climate models and projections were selected to capture a range of future climates at the conterminous scale: least warm projection, hottest projection, driest projection, and wettest projection, and one projection that reflected the middle of these ranges. The core model projections to be used in the 2020 RPA Assessment under RCP 4.5 and RCP 8.5 are: Least Warm-MRI-CGCM3; Hot-HadGEM2-ES; Dry-IPSL-CM5A-MR; Wet-CNRM-CM5; Middle-NorESM1-M. Future climates at mid-century (2041-2070) are summarized for the conterminous United States. The data are available at the USDA Forest Service Research and Development Data Archive.

This paper presents several nonlinear formulations for land allocation that optimize spatial layout for a single time period and that have the property that the number of choice variables increases linearly with the level of spatial resolution. Two nonlinear models are presented: one that accounts for spatial patterns with a cellular grid, and an alternative that uses geometric shapes. The formulations account for four criteria important to wildlife: the amount of edge, the juxtaposition of different habitat types for cover versus feeding needs, the dispersal distance between favorable habitats, and the minimum size of a patch of habitat. Case examples demonstrate the selection of different sizes of cuts as well as different spatial distributions of the cuts over the landscape, in response to different habitat needs for several species of wildlife. Sensitivity analyses were performed on alternative formulations and objective function coefficients. These model formulations are initial exploratory efforts, and extensions to this study are identified. For. Sci. 38(3):489-508.

The Northern Rockies Adaptation Partnership (NRAP) identified climate change issues relevant to resource management in the Northern Rockies (USA) region, and developed solutions intended to minimize negative effects of climate change and facilitate transition of diverse ecosystems to a warmer climate. The NRAP region covers 183 million acres, spanning northern Idaho, Montana, northwestern Wyoming, North Dakota, and northern South Dakota, and includes 15 national forests and 3 national parks across the U.S. Forest Service Northern Region and adjacent Greater Yellowstone Area. U.S. Forest Service scientists, resource managers, and stakeholders worked together over 2 years to conduct a state-of-science climate change vulnerability assessment and develop adaptation options for national forests and national parks in the Northern Rockies region. The vulnerability assessment emphasized key resource areas - water, fisheries, wildlife, forest and rangeland vegetation and disturbance, recreation, cultural heritage, and ecosystem services - regarded as the most important for local ecosystems and communities. Resource managers used the assessment to develop a detailed list of ways to address climate change vulnerabilities through management actions. The large number of adaptation strategies and tactics, many of which are a component of current management practice, provide a pathway for slowing the rate of deleterious change in resource conditions. Part 1 of this publication

Native and agricultural forests in the Northern Plains provide ecosystem services that benefit human society—diversified agricultural systems, forest-based products, and rural vitality. The impacts of recent trends in temperature and disturbances are impairing the delivery of these services. Climate change projections identify future stressors of greater impact, placing at risk crops, soils, livestock, biodiversity, and agricultural and forest-based livelihoods. While these native and agricultural forests are also a viable option for providing mitigation and adaptation services to the Northern Plains, they themselves must be managed in terms of climate change risks. Because agricultural forests are planted systems, the primary approaches for reducing risks are through design, plant selection and management. For native forests, management, natural disturbances, and collaboration of multiple ownerships will be needed to address key risks.

Climate influences the ecosystem services we obtain from forest and rangelands. An understanding of how climate may change in the future is needed to consider climate change in resource planning and management. In this chapter, we present the current understanding of the future changes in climate for the Northern Rockies region. Projected climate was derived from climate models in the Coupled Model Intercomparison Project version 5 (CMIP5) database, which was used in the most recent Intergovernmental Panel on Climate Change reports. Climate models project that the Earth's current warming trend will continue throughout the twenty-first century in the Northern Rockies. Compared to observed historical temperature, average warming across the Northern Rockies is projected to be about 2-3 degrees C by 2050, depending on greenhouse gas emissions. Seasonally, projected winter maximum temperature begins to rise above freezing in the mid-twenty-first century in several parts of the region. Projections for precipitation suggest a slight increase in the future, but precipitation projections, in general, have much higher uncertainty than those for temperature.

Federal investments by U.S. agencies to enhance climate resilience at regional scales grew over the past decade (2010s). To maximize efficiency and effectiveness in serving multiple sectors and scales, it has become critical to leverage existing agency-specific research, infrastructure, and capacity while avoiding redundancy. We discuss lessons learned from a multi-institutional regional climate response collaborative that comprises three different federally supported climate service entities in the Rocky Mountain west and northern plains region. These lessons include leveraging different strengths of each partner, creating deliberate mechanisms to increase cross-entity communication and joint ownership of projects, and placing a common priority on stakeholder-relevant research and outcomes. We share the conditions that fostered successful collaboration, which can be transferred elsewhere, and suggest mechanisms for overcoming potential barriers. Synergies are essential for producing actionable research that informs climate-related decisions for stakeholders and ultimately enhances climate resilience at regional scales.

This report is an authoritative assessment of the science of climate change, with a focus on the United States. It represents the second of two volumes of the Fourth National Climate Assessment, mandated by the Global Change Research Act of 1990.

The planning units of the National Forest System are beginning to revise their existing land management plans using the 2012 Forest Service regulations.Ecological integrity is a central concept to the regulations.However, implementing the concept is challenging in light of climate change.Historical ecology, particularly the concept of natural range of variation, informs planning for ecological integrity and climate change.This report discusses a March 2016 workshop held for the Intermountain Region to address ecological integrity, NRV, and climate change, all high priority topics for land management planning.It describes presentations included in the workshop on the evolution of the concept of natural range of variation, the 2012 planning rule, and data considerations.As part of the workshop, we developed a worksheet that managers and planners may use to consider ecological integrity, climate change, and natural range of variation.This report summarizes the use of this worksheet for two ecosystems of interest to the region: spruce-fir and alpine vegetation.We also provide recommendations, including to consider natural range of variation as a tool for planning for ecological integrity.

of the Interior's Integrated Rangeland Fire Management Strategy with long-term strategic conservation actions in the sagebrush biome.The Science Framework provides a multiscale approach for prioritizing areas for management and determining effective management strategies within the sagebrush biome.The emphasis is on sagebrush (Artemisia spp.) ecosystems and Greater sage-grouse (Centrocercus urophasianus).The approach provided in the Science Framework links sagebrush ecosystem resilience to disturbance and resistance to nonnative, invasive plant species to species habitat information based on the distribution and abundance of focal species.A geospatial process is presented that overlays information on ecosystem resilience and resistance, species habitats, and predominant threats and that can be used at the mid-scale to prioritize areas for management.A resilience and resistance habitat matrix is provided that can help decisionmakers evaluate risks and determine appropriate management strategies.Prioritized areas and management strategies can be refined by managers and stakeholders at the local scale based on higher resolution data and local knowledge.Decision tools are discussed for determining appropriate management actions for areas that are prioritized for management.Geospatial data, maps, and models are provided through the U.S. Geological Survey (USGS) ScienceBase and Bureau of Land Management (BLM) Landscape Approach Data Portal.The Science Framework is intended to be adaptive and will be updated as additional data become available on other values and species at risk.It is anticipated that the Science Framework will be widely used to: (1) inform emerging strategies to conserve sagebrush ecosystems, sagebrush dependent species, and human uses of the sagebrush system, and (2) assist managers in prioritizing and planning on-the-ground restoration and mitigation actions across the sagebrush biome.